With Prince of Persia: Sands of Time already in production, it seems that Hollywood has decided to go forward with even more video game adaptations. Here's why they won't work:
1. The Hollow Avatar: the protagonist of your average game is deliberately devoid of personality (e.g., Master Chief of Halo). In some cases, the protagonist doesn't even speak their own lines of dialogue. This hollow avatar design draws the player into the game by encouraging the projection of their own personality and voice onto the the main character. But when shifted to the medium of film, the hollow avatar comes across as nothing more than what it is; an empty character devoid of motivation or personality. This goes to the heart of how film, a passive form of entertainment, differs from games, an interactive form of entertainment.
2. Repetitive Risk-Taking: all games are essentially built around some type of risk-taking, whether it's jumping from one moving platform to another or shooting Nazis. Generally, this risk-taking is quite repetitive. Sure, game designers can shake things up a little with customizable characters, boss battles, diverse level design, and any number of other tricks, but at the end of the day most games are built around a risk-taking scenario that is repeated many times over. If a game is designed correctly, the player doesn't get bored because an element of danger is always present, in other words the player accepts the repetitiveness because the risk always feels genuine. Film, however, has a much more difficult time pulling off repetitive risk-taking scenarios, because the viewer is removed from the danger. A passive moviegoer will get bored very quickly watching a character face the same danger again and again and again. Repetitiveness lies at the core of games, but it is the death of film.
2. The Dying Factor: in games, you generally die a lot until you figure out what to do. In film, it's pretty unusual for a character to die and then get back up because they had an extra life. The dying factor helps to explain why the adaptation of the survival horror game Silent Hill, which was a beautifully shot horror film, was not in any way scary. In the game, the main character is solitary for most of the story. This isolation, combined with the fact that the character could get killed at any moment, adds tension to the gameplay. The film attempted to replicate this feature, and kept the main character isolated for much of its runtime. However, if you kill the main character, then the movie's basically over. Most viewers understand this, even if only on a subconscious level, which is why none of the dangers the character faced felt remotely scary. There was no believable way for her to die and the movie to go on. That's why most horror films have big casts, which translates into a high body count and uncertainty as to who will live.
Perhaps Prince of Persia will find a way to break the trend of crappy video game adaptations. But I'm not holding out much hope. There's only so many times you can watch a guy run along a wall.